LEMON Manuals: Even more car manuals for everyone
Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P1374: 3X Reference Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Start engine. Allow the engine to idle for 2 minutes. Observe the DTC information with a scan tool. Does the DTC fail this ignition cycle? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC or within the parameters observed in the Freeze Frame/Failure Records. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect the 6-way ignition control module connector. Remove the injector fuse. Turn ignition on, with engine off. Momentarily probe the 3X reference signal circuit at the ignition module harness connector with a test light connected to B+. Observe the Engine Speed parameter with a scan tool. Is an Engine Speed displayed? If yes, go to step  8. If no, go to next step.
  5. Did the test light illuminate? If yes, go to step  7. If no, go to next step.
  6. Turn ignition off. Disconnect the PCM. Turn ignition on, with engine off. Test the 3X reference circuit of the ignition control module for an open or a short to voltage. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  7. Turn ignition off. Disconnect the PCM. Test the 3X reference circuit of the ignition control module for a short to ground. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  8. Test for an intermittent and for a poor connection at the ignition control module. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  9. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  10. Replace the ignition control module. After repairs, go to step  12.
  11. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  12. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  13. Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
scientia non olet · About LEMON Manuals